Amperage ramps up then drops to zero

Started by silverstr8p, August 24, 2019, 04:25:50 PM

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silverstr8p

I'm running a Midnite Classic controller with 970 Watt, 24V array, into a 12V load of 4x 125Ah AGM batteries hanging off a Xantrex inverter.

The amperage ramps up to around 44 amps, then suddenly drops to zero, then repeats. I have a video of it here:

https://youtu.be/nAMLfO_dpzM

I'm just building it, so the installation is rough, but I want to figure out if this is normal, or whether there are issues. I've run numerous other Morningstar controllers into AGM's and they didn't seem to do this.

Westbranch

not normal in my experience...

Did you set a max limit for the charge Amps or limited the max. volts out from the Classic?
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

ClassicCrazy

#2
It would probably be more helpful to try and  diagnose if you had video of the Classic MNGP screen since it would show more info - state of charge, input voltage , AH, and battery voltage all at the same time.

I didn't see it just drop suddenly to zero - I saw the power scaling slowly back before it did .  So hard to say since there is no way to know what the state it was in when it did that  and couldn't tell what the battery voltage was doing .

Have you checked all your connections to see that they are tight like on breakers and other places in system ?  Also feel your batteries to see if any of those AGM are getting warmer than others.

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

bee88man

Is the Classic new and just out of the box?...there is a start-up procedure in order to set it up for it's initial run.

ClassicCrazy

Quote from: silverstr8p on August 24, 2019, 04:25:50 PM
I'm running a Midnite Classic controller with 970 Watt, 24V array, into a 12V load of 4x 125Ah AGM batteries hanging off a Xantrex inverter.

The amperage ramps up to around 44 amps, then suddenly drops to zero, then repeats. I have a video of it here:

https://youtu.be/nAMLfO_dpzM

I'm just building it, so the installation is rough, but I want to figure out if this is normal, or whether there are issues. I've run numerous other Morningstar controllers into AGM's and they didn't seem to do this.

I just read your post again and don't quite understand your system. Can  you explain more in detail how this is wired up ?
Is the charging from the Classic going right to the batteries ?

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

silverstr8p

Thanks all for the information.

@Westbranch I bought it used on consignment from the local solar dealer guy, he said he tested it and set it up for my application. I will check the DIP switches (there's a ton of them, like 20) and report back. He seems pretty knowledgeable in general and had good confidence in the condition of this unit, claims he tested it. I called him with the symptoms. He thought this may have something to do with the MPPT function, what do you all think, is that possible it's just "searching" for the best charge situation for a given load? I really don't understand how that could be the case, but open to learn. The battery voltage (on both the analog and digital volt meters permanently wired in, shown in the video) don't seem to fluctuate much when this behavior is happening.

@ClassicCrazy It has the cutout for the screen, but there's nothing in there besides a blackout plate, so it doesn't have a readout, just a few LED lights on the front that blink every once in awhile, like maybe once a minute or two apart. The batteries aren't getting warm. I checked for voltage drop across all of the inline connections from the charge controller to the batteries and there's almost none (like around 0.05VDC with my horrible meter), and they don't appear to be getting warm or discoloring the insulation suggesting they're too hot.

The output of the Classic (via 6 gauge stranded wire with soldered on connectors) goes to a 50A Ammeter (shown with blue plastic background on video), then a 50A DC breaker, then a terminal block, then a short wire to the battery post wire as it connects to the + and - terminal on the Xantrex pure sine wave 2kW inverter. The wire coming from the VMax solar AGM batteries is probably 3/4" thick and about 7 feet long, and has a huge fuse inline on the positive lead. Also hooked to the + and - posts on the Xantrex is a Morningstar Tri-Star acting as a dump load into a couple giant resistors about a foot long.

ClassicCrazy

Your system seems like it is not typical . It almost seemed to me when I first saw it that something else was messing with the way the Classic is sweeping for MPPT . Could be that dump load .
Hard to say which model Classic you have - there were different versions of them - there was a Classic Lite that did not come with MNGP just an LED panel but from what you describe it could be a different model that just had the MNGP removed.
I guess the dip switches seem to indicate a Classic Lite ? I never had that model but others may be familiar with it. You should get a photo or write down each position of the dip switches and then look at the Classic Lite manual . If it is a Classic Lite you can hook up computer and use the Local Status App to monitor and program ( I think if dip switch is in proper position to allow that ).
You may also want to take some photos of your wiring or maybe better yet draw out a schematic of your wiring to all the devices and batteries on your system.
Don't have enough info now to know what is happening with your system because all the setpoints of your Classic or even the model are unknown. Also there is no way to know how old the firmware is in it and that has had many revisions for the better over the years. You should be able to see what the firmware is if you get the Local Status app going with it.

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

silverstr8p

I believe it's a Classic Lite. I generated a drawing of my setup and attached it, let me know what other detail it needs, or whether something is hooked up wrong. I will go get a picture of the DIP switches and the manual page on them and see if that's right.


ClassicCrazy

Why do you have a diversion load to resistors ?
Also not sure if you really have the batteries wired up in series like that or if it is the simplicity for your drawing. If they are like that there is a better way to wire the batteries to ensure they get a more equal distribution of charge.
http://www.smartgauge.co.uk/batt_con.html
Best practices is you should have a breaker on the positive input if you don't.
And if you have more than two PV there should be a combiner box with breakers.

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

silverstr8p

#9
Here's a picture of the DIP switches and the label on what they're supposed to mean. I need to dig into the manual to learn more. I didn't realize there was an ethernet connection/web server on this box that I could get into, I'll have to look at that and see what the settings are for this unit. I don't actually know where the ethernet connection is, I guess it must be under the front cover?

My drawing probably isn't clear, but all the reds on the batteries are connected together and so are the blacks, so all my batteries are in parallel.

Right now I'm running my solar inputs through a terminal strip linking them all together, but I'm in the process of ordering DC breakers for each input, I just haven't gotten them from the local guy yet, I guess that will do the same thing as a combiner?

I was told to get a diversion load to prevent over-charging, but I'm in no particular danger of that, since my batteries never really get fully charged as I have it set up, now, which one of the issues I'm trying to fix. Should I disconnect that as a troubleshooting step? I have more panels I can hook up after I figure out the current problem.

Vic

#10
Hi Silver..,

It looks like Dip 5 & 6 are ON,   this is Fld3,  Pg 58 in the 2056 version of the manual here   ...

Regarding the PV breakers that Larry mentioned,   just make sure that they are DC-Rated.   It is convenient to use a MidNite Combiner box,   that accepts the MNEPV (DIN Rail style) breakers  ...   here is a bit of info:
  would suggest using the MidNite MNEPV DC breaker,   with a maximum current rating equal to the PV manufacturer's "Maximum Fuse Rating",   "Maximum Reverse Current",   or similar words.   Here is a Link for this breaker from a  reputable supplier:
https://www.solar-electric.com/midnite-solar-mnepv-15-amps-circuit-breaker.html

Here is a MidNite Combiner for six PV strings,  maximum from the same supplier:
https://www.solar-electric.com/mnpv6.html


Agree also,   that you do NOT need the MS 45 Diversion Controller,   as,   the Classic will do a great job in keeping  your batteries fully-charged,   without overcharging,  when you have the charge parameters correctly set.

The Ethernet port is under the cover,   and is a standard RJ-45  (or whaterever the number is).

FWIW,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

bee88man

Might try without the Morningstar diversion with 2 big resistors connected into the circuit...back to bascics...

FNG

I suspect the diversion is hitting hard and the classic sees it and re sweeps, What resistance value are those resistors?

silverstr8p

#13
This morning I disconnected the diversion load, there appears to be no change, though I will continue to monitor. I didn't get a chance to use the app to check the config yet, but will check and report back. Do my DIP switches look basically sane? Is it possibly an old firmware issue? I still wonder what's actually happening, seems like something is sensing the current is too high and resetting itself? In early morning when the charge is around 18Amp, it does it way less frequently.

silverstr8p

Okay, here's some screen shots, looks like it's a Classic 250V, does anything look wrong with these settings? It would only allow me four attachments, though I have more if needed.

Do I need to have an earth ground, or will the battery negative alone work?

I don't have the battery temp sensor hooked up, is that a requirement?